1. Field of the Invention
An ejector structure is removably inserted within a reusable type syringe and is adapted to accomplish separation of a needle structure from the distal end of the syringe after use without necessitating the handling of the needle or distal end of the syringe to which the needle is mounted.
2. Description of the Prior Art
The use of needles in both the dental and medical profession for the injection (or removal) of bodily fluid into the human body is of course extremely widespread and a common practice in patient care. In dentistry, it is normal practice to inject a local anesthetic so that the required procedures can be accomplished without undue pain or discomfort to the patient. Due to the advances in modern technology, numerous structural modifications have been made with the hypodermic syringe and the like. Numerous structures are presently in use which are now intended and designed to be disposable after a single use in order that infectious and contagious deceases cannot be spread from one patient to another such as when a needle is reused. However, particularly in the field of dentistry, a reusable syringe is commonly used to apply the above-noted anesthetic. Such a conventional syringe structure includes an elongated barrel having a slot extending along at least a portion of one wall thereof and communicating with the interior for the insertion of a cartridge containing the fluid intended to be injected. This type of syringe also includes a plunger having a barbed or spiked distal end which moves telescopically along the interior of the barrel and engages a stopper structure associated with the cartridge for purposes of driving or forcing the contents of the cartridge out through an attached hub portion of a needle. The hub portion is removably secured to an open distal end of the barrel by a threaded engagement therewith. Forcing of the proximal end of the plunger, using pressure exerted thereon both by the thumb and fingers, forces the plunger telescopically along the interior of the barrel. This movement of the plunger also forces the stopper within the cartridge to travel along its interior until the desired amount of fluid passes therefrom into the patient through the attached needle.
After use, it is common practice for medical personnel to detach, as by unscrewing or the like, the hub portion of the needle from the distal end of the barrel for purposes of disposal. However, such handling of the needle structure for purposes of detachment from the barrel has resulted in inadvertent contact with the sharpened point of the needle. This obviously subjects the medical personnel handling the needle and syringe to the spreading of contagious or infectious deceases. Such risks have become particularly important in recent years due to the spread of potentially fatal deceases, such as but not limit to ACQUIRED IMMUNE DEFICIENCY SYNDROME (AIDS). The latter decease is of course of particular concern since there is no known cure. Further, it has been scientifically established that one method of transferring this decease is through the use of contaminated needles.
Accordingly, there is a need in the medical and dental profession as well as the associated instrument industry for a structure or assembly capable of being used with a nondisposable syringe structure of conventional design which allows for the separation and/or ejection of the needle from the distal end of the barrel of the syringe subsequent to use thereof without requiring handling of the needle or touching of the syringe in the area of the distal end thereof. Such separation of the previously connected hub portion of the needle and therefore ejection of the needle itself may further be accomplished without recapping the used needle or mounting any type of protective cover over the sharpened end thereof.
A preferred solution to the above set forth problems should be particularly adapted for use in combination with a reusable or permanent type syringe particularly of the type to apply local anesthetic, such as Novocain or the like, to inner portions of the mouth, through injection. Such means of safely separating or ejecting the hub portion of the needle from the syringe is of course required since the typical syringe of the type used in dental procedures of the type set forth above are not intended to be disposable.